Why were Séralini’s findings controversial?

Séralini’s study was the
first and only attempt to follow up Monsanto’s study on the same GM maize.
Séralini’s team wanted to find out whether the signs of liver and kidney
toxicity found in the GM maize-fed rats in Monsanto’s study were of negligible
importance, as Monsanto claimed, or developed into serious disease. They found
that the signs of toxicity seen in the Monsanto study escalated into serious
organ damage.

Séralini designed his study as a direct follow-up to a
previous study on the same GM NK603 maize conducted by the developer company,
Monsanto.[1]

These differences in the GM maize-fed group
could have been interpreted as signs of toxicity and the onset of chronic
illness. But the Monsanto authors dismissed the findings as not related to the
GM maize and as not “biologically meaningful”. The European Food Safety
Authority (EFSA) accepted Monsanto’s interpretation.[2]

Séralini’s study was the first attempt to
follow up Monsanto’s study and to find out whether the differences found in the
GM maize-fed rats really did not matter, as Monsanto claimed, or developed into
serious disease. The study found that the signs of liver and kidney toxicity
seen in the Monsanto study escalated into serious organ damage.

Séralini’s study proved that Monsanto’s and EFSA’s view
that the changes seen in Monsanto’s study were not biologically meaningful was
incorrect. It also showed that 90-day studies are not sufficient to evaluate
the long-term health effects of GM foods and threw into question all GMO
approvals granted on the basis of such studies.

[2] European
Food Safety Authority (EFSA) (2003). Opinion of the Scientific Panel on
Genetically Modified Organisms on a request from the Commission related to the
safety of foods and food ingredients derived from herbicide-tolerant
genetically modified maize NK603, for which a request for placing on the market
was submitted under Article 4 of the Novel Food Regulation (EC) No 258/97 by
Monsanto (QUESTION NO EFSA-Q-2003-002): Opinion adopted on 25 November 2003.
EFSA Journal 2003(9): 1–14.